Mysost (Whey) Cheese: Norwegian Brown Cheese

Mysost translates literally as “whey cheese.” When you set milk with rennet, the solids knit into curd and the rest drains away as whey — a thin, sweet, pale-yellow liquid that still carries most of the milk’s lactose plus a little residual protein and fat. Mysost is what you get when you drive off that water over a long, slow boil. As the whey reduces, the lactose concentrates and the heat pushes it through a Maillard and caramelization reaction, turning the mass brown and sweet. No coloring, no sugar, and no aging are required — just time and heat.

“Brunost” (brown cheese) is the umbrella term; the members differ mainly by which milk supplies the whey, whether cream is added, and how far it is boiled. Getting the names straight helps you know what you are actually making.

Not all whey works. Mysost depends on the whey being both sweet — meaning full of intact lactose to caramelize — and fresh, so it has not soured before you start. This rules out the acid whey most home dairy leaves behind.

The method is simple but slow: strain, reduce, and stir. Plan for an unhurried afternoon — the whey has to lose most of its water before it becomes cheese, and the last stretch needs your full attention so it does not scorch.

1. 1
   Strain the whey Pour your fresh sweet whey through fine cloth or a mesh sieve to catch stray curd. Start with a large, wide, heavy-bottomed pot — more surface area means faster evaporation.
2. 2
   Simmer and reduce Bring the whey to a gentle rolling simmer (around 85–95°C / 185–205°C) and hold it there for 2–4+ hours. Volume will shrink dramatically as the water leaves and the liquid deepens from pale yellow to tan to brown.
3. 3
   Add cream and sugar (optional) For a richer, softer, fløtemysost-style result, stir in a splash of cream partway through, and if you like a deeper caramel note, a small spoon of sugar near the end. Both are optional — the whey caramelizes on its own.
4. 4
   Stir constantly near the end Once it thickens to a loose sauce, drop the heat and stir without stopping, reaching the corners and base of the pot. This is where scorching happens — a thick mass sitting on hot metal burns in seconds.
5. 5
   Whisk when thick As it reaches a thick, fudge-like paste, whisk or beat it to smooth out any grain and work in a little air. It should look glossy and hold soft peaks off the spatula.
6. 6
   Mold and cool Pour or press the hot mass into a mold or small loaf tin. Let it cool completely, then chill — it firms up as it cools into a sliceable block.

Manage your expectations before you commit an afternoon. Whey is mostly water, so even a big pot boils down to a modest block. You start with almost as much whey as you had milk — roughly 85–90% of the original volume drains off as whey — but only about 6–7% of that whey is solids, and you lose a little to the pot besides.

In practice a few litres of whey yields a small block — enough for a week of thin slices, not a wheel. If you want to plan a batch and see how much whey a given amount of milk leaves behind, run the numbers first.

Finished mysost is firm but a touch softer than Gouda, dense and slightly fudgy, with a smooth body if you whisked it well. The flavor is sweet and unmistakably caramel-like, with a dairy tang that grows sharper in the goat-milk versions. It is closer to a sweet confection than a savory cheese, which shapes how it is eaten.

Most mysost failures trace back to the last half hour of cooking, when the mixture is thick and unforgiving. Here is how to read and fix the common ones.